Twenty-two people with diabetes with sensor-assisted insulin pump participated in a pragmatic pilot study. After 2 weeks of regular insulin (without mealtime pre-bolus) participants switched to Fiasp (with fast-bolus setting where appropriate [Medtronic 640G pump]).

The glycemic peak after breakfast was significantly lower using Fiasp, albeit a small difference in absolute terms (blood glucose peak relative to before-breakfast value: 3.09 [Fiasp] vs 3.80 [regular insulin] mmol/l). Adjustments are necessary before Fiasp can be applied: insulin action starts earlier but also reaches its end of action earlier. The short duration of this study may explain why the time of blood glucose within target range was shorter with Fiasp vs regular insulin. Fiasp seems safe: there were not more hypoglycaemia events than expected. There even seemed to be more advantages for 7 youths in the age range of 12 to 7 years. The fast bolus-setting on the Medtronic 640G is being experienced as unpleasant by 5 of 9 users who tried this with Fiasp.

The small study size is a limitation of this study. Also we observed a large individual variation in the effect of/reaction to Fiasp. We did not study other mealtimes as many more variables would be involved. Summarizing, Fiasp may be a good alternative for people with diabetes struggling with mealtime peaks.